arXiv subjects

X. B. Gao

Publications and source records attributed to X. B. Gao.

101 records · Page 6Linked to original sources

arXiv2024

Observation of $ψ(3686) \to Ω^- K^+ \barΞ^0 $+c.c

Using $(27.12 \pm 0.14) \times 10^{8}$ $ψ(3686)$ events collected with the BESIII detector at BEPCII, the decay of $ψ(3686) \to Ω^- K^+ \barΞ^0 +c.c.$ is observed for the first time. The branching fraction of this decay is measured to be $\mathcal{B}_{ψ(3686) \to Ω^- K^+ \barΞ^0 +c.c.}=(2.78 \pm 0.40 \pm 0.18 ) \times 10^{-6}$, where the first uncertainty is statistical and the second is systematic. Possible baryon excited states are searched for in this decay, but no evident intermediate state is observed with the current sample size.

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arXiv2024

Search for $ΔS=2$ nonleptonic hyperon decays $Ω^-\toΣ^{0}π^{-}$ and $Ω^-\to nK^{-}$

Using $(27.12 \pm 0.14) \times 10^{8}$ $ψ(3686)$ events collected by the BESIII detector at the center-of-mass energy of $\sqrt{s} = 3.686$ GeV, we search for the first time for two nonleptonic hyperon decays that change strangeness by two units, $Ω^-\toΣ^{0}π^-$ and $Ω^-\to nK^{-}$. No significant signal is observed. The upper limits on their decay branching fractions are determined to be $\mathcal{B}(Ω^-\toΣ^{0}π^-) < 5.4\times 10^{-4}$ and $\mathcal{B}(Ω^-\to nK^{-}) < 2.4\times 10^{-4}$ at the $90\%$ confidence level.

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arXiv2024

Observation of $D \to a_{0}(980)π$ in the decays $D^{0} \rightarrow π^{+}π^{-}η$ and $D^{+} \rightarrow π^{+}π^{0}η$

We report the first amplitude analysis of the decays $D^{0} \to π^{+} π^{-} η$ and $D^{+} \rightarrow π^{+}π^{0}η$ using a data sample taken with the BESIII detector at the center-of-mass energy of 3.773 GeV, corresponding to an integrated luminosity of 7.9 ${\rm fb}^{-1}$. The contribution from the process $D^{0(+)} \to a_{0}(980)^{+} π^{-(0)}$ is significantly larger than the $D^{0(+)} \to a_{0}(980)^{-(0)} π^{+}$ contribution. The ratios $\mathcal{B}(D^{0} \rightarrow a_{0}(980)^{+}π^{-})/\mathcal{B}(D^{0} \rightarrow a_{0}(980)^{-}π^{+})$ and $\mathcal{B}(D^{+} \rightarrow a_{0}(980)^{+}π^{0})/\mathcal{B}(D^{+} \rightarrow a_{0}(980)^{0}π^{+})$ are measured to be $7.5^{+2.5}_{-0.8\,\mathrm{stat.}}\pm1.7_{\mathrm{syst.}}$ and $2.6\pm0.6_{\mathrm{stat.}}\pm0.3_{\mathrm{syst.}}$, respectively. The measured $D^{0}$ ratio disagrees with the theoretical predictions by orders of magnitudes, thus implying a substantial contribution from final-state interactions.

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arXiv2024

Measurement of the Born cross section for $e^{+}e^{-}\to ηh_c $ at center-of-mass energies between 4.1 and 4.6\,GeV

We measure the Born cross section for the reaction $e^{+}e^{-} \rightarrow ηh_c$ from $\sqrt{s} = 4.129$ to $4.600$~GeV using data sets collected by the BESIII detector running at the BEPCII collider. A resonant structure in the cross section line shape near 4.200~GeV is observed with a statistical significance of 7$σ$. The parameters of this resonance are measured to be \MeasMass\ and \MeasWidth, where the first uncertainties are statistical and the second systematic.

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arXiv2024

Search for a massless particle beyond the Standard Model in the $Σ^+\rightarrow p+{\rm invisible}$ decay

A massless particle beyond the Standard Model is searched for in the two-body decay $Σ^+\rightarrow p+{\rm invisible}$ using $(1.0087\pm0.0044)\times10^{10}$ $J/ψ$ events collected at a center-of-mass energy of $\sqrt{s}=3.097$ GeV with the BESIII detector at the BEPCII collider. No significant signal is observed, and the upper limit on the branching fraction $B(Σ^+\rightarrow p+{\rm invisible})$ is determined to be $3.2\times10^{-5}$ at the 90% confidence level. This is the first search for a flavor-changing neutral current process with missing energy in hyperon decays which plays an important role in constraining new physics models.

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arXiv2024

Evidence of the $h_c\to K_S^0 K^+π^-+c.c.$ decay

Based on $(2.712\pm0.014)\times10^9$ $ψ(3686)$ events collected by the BESIII collaboration, evidence of the hadronic decay $h_c\to K_S^0K^+π^-+c.c.$ is found with a significance of $4.3σ$ in the $ψ(3686)\toπ^0 h_c$ process. The branching fraction of $h_c\to K_S^0 K^+π^- +c.c.$ is measured to be $(7.3\pm0.8\pm1.8)\times10^{-4}$, where the first and second uncertainties are statistical and systematic, respectively. Combining with the exclusive decay width of $η_c\to K\bar{K}π$, our result indicates inconsistencies with both pQCD and NRQCD predictions.

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arXiv2024

First observation of the decay $Λ^+_c\to nK^{0}_{S}π^+π^0$

Based on 4.5 fb$^{-1}$ of $e^{+}e^{-}$ collision data accumulated at center-of-mass energies between $4599.53$ MeV and $4698.82$ MeV with the BESIII detector, the decay $Λ_{c}^{+}\to nK_{S}^{0}π^+π^0$ is observed for the first time with a significance of $9.2σ$. The branching fraction is measured to be $(0.85\pm0.13\pm0.03)\%$, where the first uncertainty is statistical and the second systematic, which differs from the theoretical prediction based on isospin by 4.4$σ$. This indicates that there may be resonant contributions or some unknown dynamics in this decay.

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arXiv2024

Precise measurement of the $e^+e^-\to D_s^+D_s^-$ cross sections at center-of-mass energies from threshold to 4.95 GeV

Using the $e^+e^-$ collision data collected with the BESIII detector operating at the BEPCII collider, at center-of-mass energies from the threshold to $4.95$~GeV, we present precise measurements of the cross sections for the process $e^+e^-\to D_s^+D_s^-$ using a single tag method. The resulting cross section lineshape exhibits several new structures, thereby offering an input for coupled channel analysis and model tests, which are critical to understand vector charmonium-like states with masses between 4 and 5~GeV.

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arXiv2024

Observation of the decay $h_{c}\to3(π^{+}π^{-})π^{0}$

Based on $(2712.4\pm14.1)\times10^{6}$ $ψ(3686)$ events collected with the BESIII detector, we study the decays $h_{c}\to3(π^{+}π^{-})π^{0}$, $h_{c}\to2(π^{+}π^{-})ω$, $h_{c}\to2(π^{+}π^{-})π^{0}η$, $h_{c}\to2(π^{+}π^{-})η$, and $h_{c}\to p\bar{p}$ via $ψ(3686)\toπ^{0}h_{c}$. The decay channel $h_{c}\to3(π^{+}π^{-})π^{0}$ is observed for the first time, and its branching fraction is determined to be $\left( {9.28\pm 1.14 \pm 0.77} \right) \times {10^{ - 3}}$, where the first uncertainty is statistical and the second is systematic. In addition, first evidence is found for the modes $h_{c} \to 2(π^{+}π^{-})π^{0}η$ and $h_{c}\to2(π^{+}π^{-})ω$ with significances of 4.8$σ$ and 4.7$σ$, and their branching fractions are determined to be $(7.55\pm1.51\pm0.77)\times10^{-3}$ and $\left( {4.00 \pm 0.86 \pm 0.35}\right) \times {10^{ - 3}}$, respectively. No significant signals of $h_c\to 2(π^+π^-)η$ and $h_{c}\to p\bar{p}$ are observed, and the upper limits of the branching fractions of these decays are determined to be $<6.19\times10^{-4}$ and $<4.40\times10^{-5}$ at the 90% confidence level, respectively.

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arXiv2024

Observation of $ψ(3686)\to 3ϕ$

Using $(2.712\pm0.014)\times 10^9$ $ψ(3686)$ events collected by the BESIII detector operating at the BEPCII collider, we report the first observation of $ψ(3686)\to 3ϕ$ decay with a significance larger than 10$σ$. The branching fraction of this decay is determined to be $(1.46\pm0.05\pm0.17)\times10^{-5}$, where the first uncertainty is statistical and the second is systematic. No significant structure is observed in the $ϕϕ$ invariant mass spectra.

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arXiv2023

Observation of $χ_{cJ}\to 3(K^+K^-)$

By analyzing $(27.12\pm0.14)\times10^8$ $ψ(3686)$ events collected with the BESIII detector operating at the BEPCII collider, the decay processes $χ_{cJ} \to 3(K^+K^-)$ ($J=0,1,2$) are observed for the first time with statistical significances of 8.2$σ$, 8.1$σ$, and 12.4$σ$, respectively. The product branching fractions of $ψ(3686)\toγχ_{cJ}$, $χ_{cJ}\to 3(K^+K^-)$ are presented and the branching fractions of $χ_{cJ}\to 3(K^+K^-)$ decays are determined to be $\mathcal{B}_{χ_{c0}\to 3(K^+K^-)}$=$(10.7\pm1.8\pm1.1)$$\times10^{-6}$, $\mathcal{B}_{χ_{c1}\to 3(K^+K^-)}$=$(4.2\pm0.9\pm0.5)$$\times10^{-6}$, and $\mathcal{B}_{χ_{c2}\to 3(K^+K^-)}$=$(7.2\pm1.1\pm0.8)$$\times10^{-6}$, where the first uncertainties are statistical and the second are systematic.

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